B-MAX4 X-shock tapered piston BM-S116TA by Yokomo  [BM-S116TA]

Tapered X-piston for precise damping control

This optional X-shock tapered piston is designed to change the damping balance between extension and compression by making one side of the piston tapered. The asymmetric profile gives tuners a simple mechanical way to bias shock behavior without changing oil viscosity or spring rates.

Orientation matters: fit the tapered face upward on front shocks to increase front load transfer during deceleration, and fit the tapered face downward on rear shocks to reduce rear breakaway risk when the car rolls in a corner. The piston has six holes with a 1.1mm hole pattern, and a 1.0mm type (BM-S106T?400) is listed as an alternative in the source.

Use this piston as part of incremental setup changes: swap one piston at a time, test lap behavior, and record which orientation produces the desired understeer or oversteer correction. The component is an RC-scale shock piston intended for tuning only.